NYU School of Medicine, Erasmus University Medical Center and New York State Department of Health respond to PA-12-185, proposing to study prenatal and childhood phthalate and bisphenol A (BPA) exposures in relationship to fetal growth, body mass, insulin resistance, fat mass and blood pressure in childhood. Di-2- ethylhexylphthalate (DEHP) is a high-molecular weight phthalate ester commonly found in processed foods, and mono-(2-ethylhexyl) phthalate increases expression of three peroxisome proliferator- , a DEHP metabolite, activated receptors which play key roles in lipid and carbohydrate metabolism, providing biological plausibility for DEHP metabolites in childhood obesity and insulin resistance. BPA, which is used to manufacture polycarbonate resin used to coat food and beverage containers, has been found to produce molecular hallmarks of obesity, and insulin resistance. Past studies of these chemical exposures and obesity have been cross-sectional and of older children and adolescents, whereas DEHP metabolites and BPA are more likely to disrupt developmental endocrine processes earlier in life and produce the chronic caloric imbalance that leads to obesity. We propose to analyze samples from three timepoints in pregnancy and two in childhood from 1431 mother-infant pairs in Generation R, a prospective, longitudinal multi-ethnic birth cohort study which has longitudinally followed 9,778 pregnancies with birth dates between 2002-2006. BPA (adjusted median 1.6 ?g/g Cr) and total DEHP metabolites (adjusted median 88.4 ?g/g Cr) in the study population are consistent with NHANES samples, increasing applicability of study findings to the US context. The PI, L. Trasande, is a nationally renowned expert in children's environmental health and first author on the first study to identify an association of an environmental chemical with childhood obesity in a nationally representative sample. The proposed study also benefits from strong support from Generation R, including the Director (V. Jaddoe), an experienced pediatric and perinatal epidemiologist with a strong record in studying early determinants of cardiovascular disease and A. Burdorf, who has developed standardized fetal growth curves for the study population. A major strength of this proposal is analysis of urine samples from three timepoints in pregnancy, which will permit examination of period-specific associations of phthalate metabolites and BPA with body mass, insulin resistance and cardiovascular risks. Analyses will be performed by K. Kannan at Wadsworth Laboratories of the New York State Department of Health, who has deep experience with precise measurement of phthalate and BPA biomarkers in urine. The proposed work endeavors to challenge existing clinical practice paradigms that obesity prevention should focus only on improved energy balance to an approach that also recognizes the role of chemical factors in the environment that may impart risk independently.